Question:  I added an index hint in my query, but the hint is being ignored.  What is the correct syntax for an index hint and how do I force the index hint to be used in my query?

Answer:  Oracle index hint syntax is tricky because of the index hint syntax is incorrect it is treated as a comment and not implemented.  Here is an example of the correct syntax for an index hint:

select /*+ index(customer cust_primary_key_idx) */ * from customer;

Also note that of you alias the table, you must use the alias in the index hint:

select /*+ index(c cust_primary_key_idx) */ * from customer c;

Also, be vary of issuing hints that conflict with an index hint.  In this index hint example, the full hint is not consistent with an index hint:

select /*+ full(c) index(c cust_primary_key_idx) */ * from customer c;

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Oracle index hint syntax